Early-Middle Miocene coralline algal assemblages from the Siirt province, southeastern Türkiye: microtaphofacies analysis and palaeoenvironmental implications

The diversity, preservation and palaeoenvironment of coralline algae in the Early-Middle Miocene Eskigarzan Limestone Member (Kayabağlar Formation) cropping out in the Siirt Province, Türkiye are evaluated by microtaphofacies analysis. The carbonate textures include grainstones, packstones, rudstones and bindstones commonly occurring with a wackestone-packstone matrix. Coralline algae from the orders Corallinales and Hapalidiales are most dominant and represented by encrusting, warty, lumpy, fruticose and layered growth-forms. Most prominent taphonomic signatures include abrasion, bioerosion, fragmentation and encrustation. The algal encrustations comprise both thin crusts and thicker, complex multi-taxa sequences. Coralline taxonomic composition, growth-forms and taphonomic signatures are examined to demarcate three microtaphofacies (MTFs I, II and III) interpreted with principal focus on the variations in sediment accumulation, water depth and hydrodynamic regime. The assessment of the coralline algae indicates two major depth ranges pertinent to the depositional palaeoenvironment – shallower Corallinales-dominant and deeper Lithothamnion-dominant denoting a deepening upwards trend.